Salmonella Typhimurium Growth in Maillard Reaction Product-mediated Acidic and Thermal Stress Conditions

Introduction: Due to increasing consumer demand for healthy foods, naturally derived antimicrobials are highly desired as alternatives to chemical preservatives in the food industry. Maillard Reaction products (MRP) have displayed antimicrobial effects on foodborne pathogens such as Escherichia coli and Listeria monocytogenes in vitro. Therefore, investigation of MRP as an antimicrobial may contribute to development of novel strategies for pathogen control.  

Purpose: The objective of this project is to evaluate the antimicrobial effect of lysine-derived MRP prepared with various carbohydrates [fructose (FL), glucose (GL), ribose (RL), sucrose (SL), and xylose (XL)] on Salmonella enterica serovar Typhimurium (ST) under acidic and thermal stress conditions. 

Methods: Water-soluble fraction of crude MRP was used in this study. ST was inoculated in brain heart infusion broth (BHIB) and acidified BHIB (pH 5.5) at 37°C. In the thermal stress assay, bacterial cells in BHIB were subjected to 42°C. All matrices were supplemented with MRP [Optical density (OD) at 420 nm = 1.03 (FL) 1.69 (GL) 0.58 (RL), 1.49 (SL), 0.81 (XL)] and the growth of ST was monitored by measuring OD_600nm for 24 h with a 96-well plate reader.

Results: In acidified BHIB, the GL significantly reduced the duration of lag phase duration (λ) of ST growth compared to the control (P < 0.05). However, under thermal stress environment, all MRPs except FL exerted significantly shorter λ of ST growth (P < 0.05). Maximum growth rate was significantly decreased in all MRP treatments compared to the control, but there were no significant differences between the MRP samples (P < 0.05). 

Significance: These findings suggest that MRP may influence the growth of ST under acidic and thermal stress conditions through complex mechanisms that require further elucidation. This can be attributed to the diversity of compounds derived from Maillard Reaction.